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View Full Version : battery suggestions? a123, lipo, NiMH?


oldshovelhead
08-12-2008, 04:14 PM
I'm turning to the pros for some advice.
After digging out my old RPM SeaMaster II EP from years and years ago I decided to get back into boating with a RTR. The Proboat Formula FASTech was my choice.
Started out running whatever NiMH packs I have that I use with my crawlers....advanced (and I use that term loosely) to a set of DTX 4200mAh packs. My mad scientist neighbor has been experimenting with the a123 cells and made a couple of packs for me.
These packs are 4600mAh four cell 6.6v packs of which I have two. I have a third pack which is a two cell 3.3v 2300mAh pack. Why I wound up with a two cell pack instead of a third four cell pack is probably a beer thing- but that's another story.
I've made adjustments to the running gear WHILE I've been experimenting with NiMH and a123. I have my drive set at it's highest negative camber (think I got that right), my trim tabs are "up" so to say, about an 1/8" from the hull bottom at the end of the tab. I've also put another battery pack lead in series so can run three separate battery packs. The Proboat esc has a 21v limit on it.
Here are a few videos, there is one of the boat on the three packs of a123 and the others are on two six cell packs of NiMH - http://www.youtube.com/oldshovelhead

So if you're still here thank You for reading my "prologue" and on to the question;
Should I pursue the a123 cells? They run much much cooler than the NiMH packs and I just need to either increase cell count or add another 4cell pack to get my voltage up to where I want it or should I go with lipo? I've steered clear from lipo for the reasons of cost and safety.
All suggestions welcomed! Even if it's "stay on the dock until you get a real boat" :laugh:
AntronX
08-12-2008, 09:54 PM
Be careful not to exceed 45 amps, that's the limit of your esc. I am using A123 myself, making another 7S2P pack. They are good cells, can handle abuse better than lipos, but lipos are little lighter.
Doozie870
08-12-2008, 09:58 PM
Its all good under 50amps load, go above that and everything gets expensive quickly.
oldshovelhead
08-13-2008, 07:59 AM
Thanks for the advice guys.

AntronX- what kind of charger are you using for your a123 cells?
AntronX
08-13-2008, 11:54 AM
I use Icharger 106B. It had 3.3V "LiFe" option in the menu. Up to 6 cells with balancing, but can charge 7 A123 cells in 6 cell "LiPo" mode. 10A max charge current or 180W, whichever comes first. Also, i don't balance my A123 pack, it does not really need it.
oldshovelhead
08-13-2008, 09:57 PM
I use Icharger 106B. It had 3.3V "LiFe" option in the menu. Up to 6 cells with balancing, but can charge 7 A123 cells in 6 cell "LiPo" mode. 10A max charge current or 180W, whichever comes first. Also, i don't balance my A123 pack, it does not really need it.


I've been eyeing the TP 610C. Just need to get a suitable power supply (like a nice variable 10a 20v my son and I can use with the slot car track for the old 1/24ths but don't tell my wife :tape: ).

Thanks again for the advice.
AntronX
08-13-2008, 11:59 PM
TP 610C is only capable of 80 watts of charging power. Even though they advertise 10A max current, you will only get 10 amps at 8 volts (80W/10A = 8V). 8 volts is only 2S LiPo. Thus maximum amperage for charging 4S2P A123 pack will be approx. 5.9 A (80W/(4*3.4V)). At 4S2P that will take about 41 - 45 minutes to charge ((4Ah/5.9A)*60min., i am getting 4 Ah (4000 mAh) of useful capacity out of my A123 pack).

106B charger does 180 watts of charging power. So that's 10A up to 18 volts or almost 5S LiPo, but at least 5S LiFe (A123). You will be able to charge your 4S2P pack at full 10 amps with this charger. Now, it will take only 24 - 28 minutes to charge 4S2P A123 pack. I have been charging my cells like this for about 3 months now, and they work fine. This charger costs the same as your's, if you know where to look :wink:
tth
08-14-2008, 12:15 AM
Check Into The Hyperion Eos1210 You Will Need A Power Supply For This Charger But It Is Well Worth The Investment. I Believe In The Swap Shop They Have One A123 Capable With An Lba10 Balancer. I Just Bought One Of These From Steven V. And I Don't Regret It At All. Will Charge
12-a123 Cells And Up To 180 Watts Also. Just My 2 Pennies.